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minix/servers/fs/mount.c
Ben Gras 7967177710 endpoint-aware conversion of servers. 
'who', indicating caller number in pm and fs and some other servers, has
been removed in favour of 'who_e' (endpoint) and 'who_p' (proc nr.).

In both PM and FS, isokendpt() convert endpoints to process slot
numbers, returning OK if it was a valid and consistent endpoint number.
okendpt() does the same but panic()s if it doesn't succeed. (In PM,
this is pm_isok..)

pm and fs keep their own records of process endpoints in their proc tables,
which are needed to make kernel calls about those processes.

message field names have changed.

fs drivers are endpoints.

fs now doesn't try to get out of driver deadlock, as the protocol isn't
supposed to let that happen any more. (A warning is printed if ELOCKED
is detected though.)

fproc[].fp_task (indicating which driver the process is suspended on)
became an int.

PM and FS now get endpoint numbers of initial boot processes from the
kernel. These happen to be the same as the old proc numbers, to let
user processes reach them with the old numbers, but FS and PM don't know
that. All new processes after INIT, even after the generation number
wraps around, get endpoint numbers with generation 1 and higher, so
the first instances of the boot processes are the only processes ever
to have endpoint numbers in the old proc number range.

More return code checks of sys_* functions have been added.

IS has become endpoint-aware. Ditched the 'text' and 'data' fields
in the kernel dump (which show locations, not sizes, so aren't terribly
useful) in favour of the endpoint number. Proc number is still visible.

Some other dumps (e.g. dmap, rs) show endpoint numbers now too which got
the formatting changed.

PM reading segments using rw_seg() has changed - it uses other fields
in the message now instead of encoding the segment and process number and
fd in the fd field. For that it uses _read_pm() and _write_pm() which to
_taskcall()s directly in pm/misc.c.

PM now sys_exit()s itself on panic(), instead of sys_abort().

RS also talks in endpoints instead of process numbers.
2006-03-03 10:20:58 +00:00

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/* This file performs the MOUNT and UMOUNT system calls.
*
* The entry points into this file are
* do_mount: perform the MOUNT system call
* do_umount: perform the UMOUNT system call
*/
#include "fs.h"
#include <fcntl.h>
#include <string.h>
#include <minix/com.h>
#include <sys/stat.h>
#include "buf.h"
#include "file.h"
#include "fproc.h"
#include "inode.h"
#include "param.h"
#include "super.h"
/* Allow the root to be replaced before the first 'real' mount. */
PRIVATE int allow_newroot= 1;
FORWARD _PROTOTYPE( dev_t name_to_dev, (char *path) );
/*===========================================================================*
* do_mount *
*===========================================================================*/
PUBLIC int do_mount()
{
/* Perform the mount(name, mfile, rd_only) system call. */
register struct inode *rip, *root_ip;
struct super_block *xp, *sp;
dev_t dev;
mode_t bits;
int rdir, mdir; /* TRUE iff {root|mount} file is dir */
int i, r, found;
struct fproc *tfp;
/* Only the super-user may do MOUNT. */
if (!super_user) return(EPERM);
/* If 'name' is not for a block special file, return error. */
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
if ( (dev = name_to_dev(user_path)) == NO_DEV) return(err_code);
/* Scan super block table to see if dev already mounted & find a free slot.*/
sp = NIL_SUPER;
found = FALSE;
for (xp = &super_block[0]; xp < &super_block[NR_SUPERS]; xp++) {
if (xp->s_dev == dev)
{
/* is it mounted already? */
found = TRUE;
sp= xp;
break;
}
if (xp->s_dev == NO_DEV) sp = xp; /* record free slot */
}
if (found)
{
printf(
"do_mount: s_imount = 0x%x (%x, %d), s_isup = 0x%x (%x, %d), fp_rootdir = 0x%x\n",
xp->s_imount, xp->s_imount->i_dev, xp->s_imount->i_num,
xp->s_isup, xp->s_isup->i_dev, xp->s_isup->i_num,
fproc[FS_PROC_NR].fp_rootdir);
/* It is possible that we have an old root lying around that
* needs to be remounted.
*/
if (xp->s_imount != xp->s_isup ||
xp->s_isup == fproc[FS_PROC_NR].fp_rootdir)
{
/* Normally, s_imount refers to the mount point. For a root
* filesystem, s_imount is equal to the root inode. We assume
* that the root of FS is always the real root. If the two
* inodes are different or if the root of FS is equal two the
* root of the filesystem we found, we found a filesystem that
* is in use.
*/
return(EBUSY); /* already mounted */
}
if (root_dev == xp->s_dev)
{
panic("fs", "inconsistency remounting old root",
NO_NUM);
}
/* Now get the inode of the file to be mounted on. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
return(err_code);
}
if ( (rip = eat_path(user_path)) == NIL_INODE) {
return(err_code);
}
r = OK;
/* It may not be special. */
bits = rip->i_mode & I_TYPE;
if (bits == I_BLOCK_SPECIAL || bits == I_CHAR_SPECIAL)
r = ENOTDIR;
/* Get the root inode of the mounted file system. */
root_ip= sp->s_isup;
/* File types of 'rip' and 'root_ip' may not conflict. */
if (r == OK) {
mdir = ((rip->i_mode & I_TYPE) == I_DIRECTORY);
/* TRUE iff dir */
rdir = ((root_ip->i_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the mount point. */
if (r != OK) {
put_inode(rip);
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
rip->i_mount = I_MOUNT; /* this bit says the inode is
* mounted on
*/
put_inode(sp->s_imount);
sp->s_imount = rip;
sp->s_rd_only = m_in.rd_only;
allow_newroot= 0; /* The root is now fixed */
return(OK);
}
if (sp == NIL_SUPER) return(ENFILE); /* no super block available */
/* Open the device the file system lives on. */
if (dev_open(dev, who_e, m_in.rd_only ? R_BIT : (R_BIT|W_BIT)) != OK)
return(EINVAL);
/* Make the cache forget about blocks it has open on the filesystem */
(void) do_sync();
invalidate(dev);
/* Fill in the super block. */
sp->s_dev = dev; /* read_super() needs to know which dev */
r = read_super(sp);
/* Is it recognized as a Minix filesystem? */
if (r != OK) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Now get the inode of the file to be mounted on. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(err_code);
}
if (strcmp(user_path, "/") == 0 && allow_newroot)
{
printf("Replacing root\n");
/* Get the root inode of the mounted file system. */
if ( (root_ip = get_inode(dev, ROOT_INODE)) == NIL_INODE) r = err_code;
if (root_ip != NIL_INODE && root_ip->i_mode == 0) {
r = EINVAL;
}
/* If error, return the super block and both inodes; release the
* maps.
*/
if (r != OK) {
put_inode(root_ip);
(void) do_sync();
invalidate(dev);
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
sp->s_imount = root_ip;
dup_inode(root_ip);
sp->s_isup = root_ip;
sp->s_rd_only = m_in.rd_only;
root_dev= dev;
/* Replace all root and working directories */
for (i= 0, tfp= fproc; i<NR_PROCS; i++, tfp++)
{
if (tfp->fp_pid == PID_FREE)
continue;
if (tfp->fp_rootdir == NULL)
panic("fs", "do_mount: null rootdir", i);
put_inode(tfp->fp_rootdir);
dup_inode(root_ip);
tfp->fp_rootdir= root_ip;
if (tfp->fp_workdir == NULL)
panic("fs", "do_mount: null workdir", i);
put_inode(tfp->fp_workdir);
dup_inode(root_ip);
tfp->fp_workdir= root_ip;
}
/* Leave the old filesystem lying around. */
return(OK);
}
if ( (rip = eat_path(user_path)) == NIL_INODE) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(err_code);
}
/* It may not be busy. */
r = OK;
if (rip->i_count > 1) r = EBUSY;
/* It may not be special. */
bits = rip->i_mode & I_TYPE;
if (bits == I_BLOCK_SPECIAL || bits == I_CHAR_SPECIAL) r = ENOTDIR;
/* Get the root inode of the mounted file system. */
root_ip = NIL_INODE; /* if 'r' not OK, make sure this is defined */
if (r == OK) {
if ( (root_ip = get_inode(dev, ROOT_INODE)) == NIL_INODE) r = err_code;
}
if (root_ip != NIL_INODE && root_ip->i_mode == 0) {
r = EINVAL;
}
/* File types of 'rip' and 'root_ip' may not conflict. */
if (r == OK) {
mdir = ((rip->i_mode & I_TYPE) == I_DIRECTORY); /* TRUE iff dir */
rdir = ((root_ip->i_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the super block and both inodes; release the maps. */
if (r != OK) {
put_inode(rip);
put_inode(root_ip);
(void) do_sync();
invalidate(dev);
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
rip->i_mount = I_MOUNT; /* this bit says the inode is mounted on */
sp->s_imount = rip;
sp->s_isup = root_ip;
sp->s_rd_only = m_in.rd_only;
allow_newroot= 0; /* The root is now fixed */
return(OK);
}
/*===========================================================================*
* do_umount *
*===========================================================================*/
PUBLIC int do_umount()
{
/* Perform the umount(name) system call. */
dev_t dev;
/* Only the super-user may do UMOUNT. */
if (!super_user) return(EPERM);
/* If 'name' is not for a block special file, return error. */
if (fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
if ( (dev = name_to_dev(user_path)) == NO_DEV) return(err_code);
return(unmount(dev));
}
/*===========================================================================*
* unmount *
*===========================================================================*/
PUBLIC int unmount(dev)
Dev_t dev;
{
/* Unmount a file system by device number. */
register struct inode *rip;
struct super_block *sp, *sp1;
int count;
/* See if the mounted device is busy. Only 1 inode using it should be
* open -- the root inode -- and that inode only 1 time.
*/
count = 0;
for (rip = &inode[0]; rip< &inode[NR_INODES]; rip++)
if (rip->i_count > 0 && rip->i_dev == dev) count += rip->i_count;
if (count > 1) return(EBUSY); /* can't umount a busy file system */
/* Find the super block. */
sp = NIL_SUPER;
for (sp1 = &super_block[0]; sp1 < &super_block[NR_SUPERS]; sp1++) {
if (sp1->s_dev == dev) {
sp = sp1;
break;
}
}
/* Sync the disk, and invalidate cache. */
(void) do_sync(); /* force any cached blocks out of memory */
invalidate(dev); /* invalidate cache entries for this dev */
if (sp == NIL_SUPER) {
return(EINVAL);
}
/* Close the device the file system lives on. */
dev_close(dev);
/* Finish off the unmount. */
sp->s_imount->i_mount = NO_MOUNT; /* inode returns to normal */
put_inode(sp->s_imount); /* release the inode mounted on */
put_inode(sp->s_isup); /* release the root inode of the mounted fs */
sp->s_imount = NIL_INODE;
sp->s_dev = NO_DEV;
return(OK);
}
/*===========================================================================*
* name_to_dev *
*===========================================================================*/
PRIVATE dev_t name_to_dev(path)
char *path; /* pointer to path name */
{
/* Convert the block special file 'path' to a device number. If 'path'
* is not a block special file, return error code in 'err_code'.
*/
register struct inode *rip;
register dev_t dev;
/* If 'path' can't be opened, give up immediately. */
if ( (rip = eat_path(path)) == NIL_INODE) return(NO_DEV);
/* If 'path' is not a block special file, return error. */
if ( (rip->i_mode & I_TYPE) != I_BLOCK_SPECIAL) {
err_code = ENOTBLK;
put_inode(rip);
return(NO_DEV);
}
/* Extract the device number. */
dev = (dev_t) rip->i_zone[0];
put_inode(rip);
return(dev);
}
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